1. Field of the invention
This invention relates to systems for identifying refrigerants. More particularly, this invention relates to systems for measuring sonic velocities and temperature coefficients of the sonic velocities as indicia of the type of refrigerant in or from an air conditioning system.
2. Description of the Related Art
Identification of the refrigerant in an air conditioning system will soon become important to the refrigeration industry because refrigerants must be reclaimed and reused, and because new refrigerants are being developed.
Until now, the automotive refrigeration industry used Refrigerant 12 (R12) exclusively in air conditioning systems. However, R12 attacks the atmospheric "Ozone layer", making it particularly damaging to the environment. Therefore, the production of R12 will be gradually discontinued. New refrigerants, such as R134a, are being developed for use in automotive air conditioning systems. However, these refrigerants are not compatible with R12 and require new air conditioning components. Existing automotive air conditioning systems will be serviced using ternary blends. In a few years, the automotive refrigeration industry will be using several different refrigerants. Already, the commercial refrigeration industry uses several different refrigerants.
If an air conditioning system has an unknown refrigerant or a mix of refrigerants and the refrigerant is vented to the atmosphere, the refrigerant in the air conditioner is of no concern. However, if the refrigerant is to be reclaimed, then it is essential to know the type of refrigerant before beginning the reclamation process. This is because once refrigerants are mixed, they cannot easily be separated. A large tank of reclaimed refrigerant is generally ruined if it contains a mixture of different refrigerants. Instead of being reused, a tank containing a mixture of different refrigerants must be incinerated.
In the past, when a refrigeration system needed service, the refrigerant was vented to the atmosphere. Because all refrigerants are greenhouse gases and because some refrigerants attack the atmospheric "Ozone layer", the practice of venting refrigerant to the atmosphere is no longer acceptable. The automotive refrigeration industry already reclaims and reuses refrigerant. The commercial refrigeration industry is now writing standards that will result in reclaiming and reusing refrigerant.